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Finding the Fourth Proportional to 878.10, 1,211.86 and 485.20

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Solution

The fourth proportional to 878.10, 1,211.86 and 485.20 is: 669.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    878.10 : 1,211.86 = 485.20 : x
  2. Step 2: Convert to fraction form
    878.10/1,211.86 = 485.20/x
  3. Step 3: Cross multiply
    878.10x = 1,211.86 × 485.20
  4. Step 4: Simplify right side
    878.10x = 587,994.47
  5. Step 5: Solve for x
    x = 587,994.47/878.10
  6. Step 6: Final answer
    x = 669.62

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.